Natural Color orthoimagery for southern Maine, including portions of Cumberland, York, Androscoggin and Sagadahoc Counties, 2009This data set consists of 0.3-meter pixel resolution (approximately 1-foot), natural color orthoimages covering the urban area footprint. An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map. The design accuracy is estimated not to exceed 3-meter diagonal RMSE (2.12m RMSE in X or Y). Each orthoimage provides imagery over a 1500-meter by 1500-meter block on the ground. There is no image overlap between adjacent files. The projected coordinate system is UTM with a NAD83 datum. The naming convention is based on the U. S. National Grid (USNG), taking the coordinates of the SW corner of the orthoimage. Task Order Number G09PD01896. USGS Contract Number 07CRCN0014. Nominal Acquisition Altitude (AGL) was 9600'. The geoid used to reduce satellite derived elevations to orthometric heights was Geoid 03. GPS coordinates are referenced to NAD83 Universal Transverse Mercator Zone 19. The maximum differential baseline length is 69373.00 meters. The mean baseline length is 25668.18 meters. Camera sensors calibration reports are included in the project report. Calibration flights are flown regularly. Natural color orthoimagery is organized in three color bands or channels which represent the red, green, and blue (RGB) portions of the spectrum. Each image pixel is assigned a triplet of numeric values, one for each color band. Numeric values range from 0 to 255. Areas where data is incomplete due to lack of full image coverage are represented with the numeric value of 0.

Natural Color orthoimagery for southern Maine, including portions of Cumberland, York, Androscoggin and Sagadahoc Counties, 2009This data set consists of 0.3-meter pixel resolution (approximately 1-foot), natural color orthoimages covering the urban area footprint. An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map. The design accuracy is estimated not to exceed 3-meter diagonal RMSE (2.12m RMSE in X or Y). Each orthoimage provides imagery over a 1500-meter by 1500-meter block on the ground. There is no image overlap between adjacent files. The projected coordinate system is UTM with a NAD83 datum. The naming convention is based on the U. S. National Grid (USNG), taking the coordinates of the SW corner of the orthoimage. Task Order Number G09PD01896. USGS Contract Number 07CRCN0014. Nominal Acquisition Altitude (AGL) was 9600'. The geoid used to reduce satellite derived elevations to orthometric heights was Geoid 03. GPS coordinates are referenced to NAD83 Universal Transverse Mercator Zone 19. The maximum differential baseline length is 69373.00 meters. The mean baseline length is 25668.18 meters. Camera sensors calibration reports are included in the project report. Calibration flights are flown regularly. Natural color orthoimagery is organized in three color bands or channels which represent the red, green, and blue (RGB) portions of the spectrum. Each image pixel is assigned a triplet of numeric values, one for each color band. Numeric values range from 0 to 255. Areas where data is incomplete due to lack of full image coverage are represented with the numeric value of 0.